The instant invention relates to an auxiliary extension member and support frame for a vehicular mounted aerial ladder assembly.
Vehicular mounted ladders, towers, and aerial lift means of various types are generally disclosed in the prior art as being comprised of the following major design types. First, ladder or tower aerial lift assemblies are exemplified by those such as taught in U.S. Pat. No. 2,936,848 to Hall, dated May 17, 1960, as well as U.S. Pat. No. 3,489,244 to Rickrode et al., dated Jan. 13, 1970, and U.S. Pat. No. 3,621,935 to Bode, dated Nov. 23, 1971. The elevation and lifting means disclosed in the aforementioned patents range from manually operable to motorized aerial lift units which were primarily designed for use by utility line installers and maintenance personnel for erecting and repairing overhead electrical transmission lines and the like, in addition to being employed by tree trimming crews, as well as construction workers and painters in accomplishing various elevated operations. As further exemplified by the aforementioned patents, said ladder or tower aerial lift assemblies may also have affixed thereto, at the uppermost terminal end thereof, a work platform which may be stationary, as shown in Bodie, or arcuately adjustable with regard to maintaining a parallel relation to the horizontal plane, as shown in Hall, or, as shown in Rickrode et al, have no platform at all.
A second general type of aerial lift design are those primarily comprised of a "boom and bucket" assembly, which may or may not be vehicular mounted, and may or may not incorporate ladder features, exemplary disclosures of which are as shown in U.S. Pat. No. 3,584,703 to Lane, dated June 15, 1971, U.S. Pat. No. 3,625,307 to Siefermann et al, dated Dec. 7, 1971, and U.S. Pat. No. 3,777,845 to Ashworth, dated Dec. 11, 1973. Bucket levelling features are also normally incorporated, generally comprised of either a hydraulically activated mechanical lever assembly operable through a series of pivot points, or secondly, simple gravitational levelling means provided by pivotal suspension of said bucket from the upper end of said boom either with or without bucket stabilizing means. Aerial lift equipment of this second general design is usually larger in size and more expensive than the first general type heretofore described, and is primarily and popularly employed in fire fighting and rescue operation types of activities.
Other aerial lift means disclosures, which may be classified in one or the other categories of the two main general designs heretofore indicated, but which teach additional aspects of the art not otherwise shown, include the following: U.S. Pat. No. 2,666,417 to Harsch, dated Jan. 19, 1954, which shows a rotatably and arcuately positionable hydraulically operated two member telescopic boom having a man-carrying cage pivotally affixed to the upper terminal end thereof, whereby said cage is maintained in a horizontal configuration by means of a double-acting hydraulic motor linkably connecting said cage and the upper terminal end of said boom so that as the boom operates said motor automatically extends and retracts a piston in direct relation to the tilt of the boom, and said cage is thereby automatically maintained in a horizontally level position. A subsequent disclosure by Harsch, in U.S. Pat. No. 2,786,723 dated Mar. 26, 1957, shows a similar structure to his earlier disclosure cited supra, but teaching a new method of employing a hydraulic cylinder unit to correlate the horizontal configuration of the cage with the pivotal movements of the boom such that said cage is automatically maintained in a level disposition at all angular articulations of said boom. Another disclosure in the aerial lift art teaching less sophisticated employment of a hydraulic piston to maintain a horizontally level cage configuration is that as shown in U.S. Pat. No. 2,724,620 to Johnson et al., dated Nov. 22, 1955.
The disclosure set forth in U.S. Pat. No. 2,815,250 to Thornton-Trump, dated Dec. 3, 1957, shows an aerial lift device comprised to two pivotally connected boom sections whereby a 180.degree. horizontally arcuate deflection capability is substantially provided for the man-carrying cage assembly pivotally affixed to the upper terminal end of the second boom section thereof, with a bell crank linkage extending from the boom structure junction to the cage through which said cage is maintained essentially in a horizontal position irrespective of the swinging movement of said booms. The disclosure by Garnett, in U.S. Pat. No. 3,196,979 dated July 27, 1965, shows means for controlling horizontal position of a man-carrying basket member pivotally affixed by means of a yoke to the end of a telescoping boom, but additionally shows a novel arrangement whereby the basket carrying arm members of the aerial lift device yoke are also pivotal rearwards whereby the transport position is one in which said basket member and yoke are folded back and said basket member rests in a stowed position upon the inner telescoping boom section. In U.S. Pat. No. 3,332,513 to Weibe, dated July 25, 1967, a mobile scaffold is shown wherein the cage member thereof remains substantially horizontal by means of a set of double-bar/double-arm linkages.
The art disclosed by Hall in U.S. Pat. No. 3,572,467 dated Mar. 30, 1971, shows a vehicular mounted telescopically extensible ladder assembly with a personnel platform pivotally affixed thereto and linkably interaffixed to a slave piston and cylinder unit whereby said platform may be stabilized or swung. Hall also teaches stowing of the retracted aerial unit rearward in the transport vehicle. A similar disclosure by, Garnett, in U.S. Pat. No. 3,767,007 dated Oct. 23, 1973, shows a pivotally mounted basket member affixed to the upper terminal end of an extensible ladder, but with the aerial unit facing vehicularly forward in the retracted stowed transport configuration, and a shock absorber type of assembly provided as a damping means to prevent sudden changes in said basket member configuration when said aerial unit is operably positioned.
Two additional disclosures showing aerial lift features of considerable interest are those set forth in U.S. Pat. No. 3,625,304 to Siefermann et al, dated Dec. 7, 1971, and the other being U.S. Pat. No. 3,710,893 to Hippach, dated Jan. 16, 1973. The Siefermann et al. disclosure shows a vehicular mounted aerial ladder assembly with a pivotally affixed cage at the upper end thereof, whereby either an electric or hydraulic power source located on the ladder provides means to automatically maintain said cage in an upright configuration relative to the horizontal position regardless of any change in incline of said aerial ladder assembly. The Hippach patent, however, shows an extendible boom and ladder assembly with a pivoted basket depending from a yoke extension affixed to the end of said boom, and further having a relatively short two-section ingress and egress ladder leading from the upper end of the main ladder into the pivotally depending basket.
It should be understood that some of the features of the instant invention have, in some cases, structural and functional similarities to teachings separately set forth in the prior art disclosures heretofore cited and briefly discussed. However, as will hereinafter be pointed out, the instant invention is distinguishable from said earlier inventions in one or more ways in that the present invention has utility features and new and useful advantages, applications, and improvements in the art of vehicular mounted articulated aerial lift and ladder assemblies not heretofore known.